1. Field of the invention
This invention generally relates to devices for measuring the pressure within gas-filled cables, especially cables used for data transmission and more particularly a multiple sensor pressure transducer capable of measuring the pressure level in a plurality of adjacent gas-filled cables.
2. DESCRIPTION OF THE PRIOR ART
The cable pressurizing technique is already known and is in widespread use by telephonic Companies and consists of admitting compressed and dehydrated air within the telephonic cables. This technique has the purpose of maintaining a high insulation resistance along the copper conductors, by preventing the outer moisture from entering the cable. Further, the pneumatic phenomena correlated to and resulting from possible air leakage from the cable are used to prevent the moisture from entering the cable, which is often due to the greater outer pressure, and to locate the place of these leakages.
The advantages resulting from the use of this technique are numberless, of which some are already known and some are to be discovered or demonstrated. The equipment and the devices used to attain the above objectives are evolving and improving making the application of these methods more and more attractive both from the standpoint of the technical performances and from the standpoint of the costs.
The improvement in performance is obtained by the use of the electronic techniques integrated by an effective system architecture and by a center software devised for taking the maximal advantage from the measurements and the surveys made by the equipment or devices installed in the field.
The optimization and the reduction of costs, especially of the labour for installing these systems, are important factors for a quick and effective diffusion thereof.
For measuring the pressure within gas-filled cables, pressure transducers are normally used which convert pressure to a measurable electric signal.
At present, the use of electronic pressure transducers is known which make use of a pair of wires belonging to the same gas-filled cable, the pressure of which is to be measured for transmitting to a remote location a signal having a frequency proportional to the pressure measured by the transducer.
Such transducer uses as basic components a sensor and a timer.
Such systems use a plurality of pressure transducers arranged along the gas-filled cable, in predetermined measuring locations. Each pressure transducer is provided with one own timer allowing the signal transmission for a limited time and in a predetermined time sequence so as to permit the pressure transducers to transmit one at a time their signals according to this sequence. Of course, these signals are supplied to a center unit which is capable of indicating for each of the received electric signals the associated pressure transducer in the same order as they are received and is adapted to supply simultaneously through the transmission line all the pressure transducers.